Stepped electrochemical cells with folded sealed portion

ABSTRACT

A pouched energy storage device can include a cell housing portion and a sealed portion. The device can also include a stack of electrodes housed within an inner region of the cell housing portion. Each electrode can have dimensions of width, length, and thickness. One or more electrodes can have at least one of the dimensions smaller than a corresponding dimension of other electrodes in the stack of electrodes. The device can also include an indentation on the cell housing portion adjacent the sealed portion. The indentation can form a stepped region in the inner region that is complimentary to the one or more electrodes having at least one of the dimensions smaller than a corresponding dimension of other electrodes in the stack of electrodes. The sealed portion can be folded onto the cell housing portion so that at least a part of the sealed portion resides in the indentation.

BACKGROUND Field

The present disclosure relates generally to energy storage devices, suchas electrochemical cells (e.g., batteries). In particular, the presentdisclosure relates to stepped electrochemical cells and packages tohouse electrochemical cell components.

Description of the Related Art

A battery typically includes a separator and/or electrolyte between ananode and a cathode. In one class of batteries, the separator, cathodeand anode materials are individually formed into sheets or films. Sheetsof the cathode, separator and anode are subsequently stacked or rolledwith the separator separating the cathode and anode (e.g., electrodes)to form the battery. Typical electrodes include electro-chemicallyactive material layers on electrically conductive metals (e.g., aluminumand copper). Films can be rolled or cut into pieces which are thenlayered into stacks. The stacks are of alternating electro-chemicallyactive materials with the separator between them.

An energy storage device, such as an electrochemical cell (e.g., abattery) can include packaging to house the electrochemical cellcomponents (e.g., the anode, cathode, separator, and/or electrolyte). Apouch pack is one example packaging for an energy storage device. Forexample, a pouched energy storage device can include a pouch pack forthe package to house the electrochemical cell components.

SUMMARY

In certain embodiments, a pouched energy storage device is provided. Thedevice can include a cell housing portion and a sealed portion. Thedevice can also include a stack of electrodes housed within an innerregion of the cell housing portion. Each electrode can have dimensionsof width, length, and thickness. One or more electrodes can have atleast one of the dimensions smaller than a corresponding dimension ofother electrodes in the stack of electrodes. The device can also includean indentation on the cell housing portion adjacent the sealed portion.The indentation can form a stepped region in the inner region that iscomplimentary to the one or more electrodes having at least one of thedimensions smaller than a corresponding dimension of other electrodes inthe stack of electrodes. The sealed portion can be folded onto the cellhousing portion so that at least a part of the sealed portion resides inthe indentation. In various embodiments, the device can include alithium ion battery, a lithium polymer battery, or a metal lithiumbattery.

In some embodiments of the device, the walls of the cell housing portioncan have a wall thickness, and the sealed portion can have a sealedportion thickness that is approximately twice the wall thickness of thewalls of the cell housing portion. In some embodiments, the device canhave a first major exterior surface, a second major exterior surface,and a device thickness extending therebetween. The sealed portion canhave a sealed portion width, a sealed portion length, and a sealedportion thickness. The device thickness can be smaller than the sealedportion width. In some examples, the sealed portion width can be in therange of about 1.5 mm to about 10 mm.

In various embodiments, the device can include a first major surface anda second major surface. The sealed portion can be folded adjacent thefirst major surface of the device. The indentation can be locatedadjacent the second major surface of the device.

In some embodiments, the device can include at least two sealedportions. The sealed portion can be folded to form multiple layers. Thesealed portion can be attached onto the cell housing portion.

In certain embodiments, a method of making a pouched energy storagedevice is provided. The method can include providing walls to define aninner region of the cell housing portion. The walls can be configured tohouse within the inner region an anode, a cathode, a separator, and anelectrolyte. The method can also include inserting a stack of electrodesinto the cell housing portion. Each electrode can have dimensions ofwidth, length, and thickness. One or more electrodes can have at leastone of the dimensions smaller than a corresponding dimension of otherelectrodes in the stack of electrodes. The method can further includeheat sealing portions of the walls to form the sealed portion. Themethod can further include folding the sealed portion onto the cellhousing portion such that part of the sealed portion resides in anindentation of the cell housing portion.

In various embodiments, the method can further include forming theindentation on the cell housing portion. The indentation can be sized toaccommodate at least part of the sealed portion. The indentation candefine a stepped region in the inner region.

In some embodiments, providing the walls can comprise providing aluminumlaminate pouch material. Heat sealing portions of the walls can comprisehermetically sealing the portions of the walls. In addition, folding thesealed portion onto the cell housing portion can include folding a firstregion of the sealed portion adjacent a first major surface of thedevice, and folding a second region of the sealed portion adjacent asecond major surface of the device. The method can also includeattaching the sealed portion onto the cell housing portion.

In certain embodiments, a pouch for an energy storage device isprovided. The pouch can include a cell housing portion and a sealedportion. The cell housing portion can have walls defining an innerregion. The walls can be configured to house within the inner region ananode, a cathode, a separator, and an electrolyte. The cell housingportion can include an indentation. The sealed portion can extend fromthe cell housing portion. The sealed portion can be folded onto the cellhousing portion such that part of the sealed portion resides in theindentation. In some embodiments, the indentation can form a steppedregion in the inner region of the cell housing portion.

In various embodiments of the pouch, the walls can be configured tohouse a lithium ion battery, a lithium polymer battery, or a metallithium battery. The walls of the cell housing portion and the sealedportion can include an aluminum laminate pouch material. In someembodiments, the walls of the cell housing portion can have a wallthickness, and the sealed portion can have a sealed portion thicknessthat is approximately twice the wall thickness of the walls of the cellhousing portion. In some embodiments, the pouch can include a firstmajor exterior surface, a second major exterior surface, and a pouchthickness extending therebetween. The sealed portion can have a sealedportion width, a sealed portion length, and a sealed portion thickness.The pouch thickness can be smaller than the sealed portion width. Insome examples, the sealed portion width can be in the range of 1.5 mm toabout 10 mm.

In various embodiments, the pouch can include a first major surface anda second major surface. The sealed portion can be folded adjacent thefirst major surface of the pouch. The indentation can be locatedadjacent the second major surface of the pouch.

In some embodiments, the pouch can include at least two sealed portions.The sealed portion can be folded to form multiple layers. The sealedportion can be attached onto the cell housing portion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1, 2, 3, 4, and 5 schematically illustrate cross-sectional viewsof example energy storage device packages with side seals;

FIG. 6A schematically illustrates a cross-sectional view of an exampleenergy storage device package with unfolded side seals in accordancewith certain embodiments described herein;

FIG. 6B schematically illustrates a cross-sectional view of the exampleenergy storage device package shown in FIG. 6A with folded side seals inaccordance with certain embodiments described herein;

FIG. 6C schematically illustrates a perspective view of an exampleenergy storage device utilizing the example package shown in FIGS. 6A-6Bin accordance with certain embodiments described herein; and

FIG. 7 schematically illustrates a flow diagram of an example method ofmaking a pouched energy storage device in accordance with certainembodiments described herein.

The examples in the figures are not drawn to scale. Features may havebeen exaggerated to illustrate certain features. For example, thethickness of certain sheets and/or walls may have been exaggerated.

DETAILED DESCRIPTION

A pouch pack can be used as packaging for an energy storage device, suchas an electrochemical cell (e.g., a battery such as a pouch cell). Thepouch can be heat sealed to hermetically (or near hermetically) sealelectrochemical cell components including an anode, a cathode, aseparator, and electrolyte within the pouch. In general, the pouch doesnot store energy and thus can be considered an inactive part of thedevice. In some instances, to maximize packaging efficiency and energydensity, minimizing the pouch footprint within a product can becritical.

FIG. 1 schematically illustrates a cross-sectional view of an exampleenergy storage device package, such as an electrochemical cell package(e.g., a battery pouch) with side seals. As shown in FIG. 1, the package100 includes a first sheet 110 a and a second sheet 110 b defining aninner region 115 to house the electrochemical cell components (notshown). The package 100 also includes two side seals 120 formed bysealing together parts of the first 110 a and second 110 b sheets. Forexample, a first sheet 110 a can be formed into a U-shaped compartmentin which to insert the electrochemical cell components. After theelectrochemical cell components are inserted, a second sheet 110 b canbe sealed to parts of the first sheet 110 a to seal the electrochemicalcell components within the inner region 115. Each side seal 120 can havea width w_(s) sufficient to seal the package 100 together such that theside seal 120 does not leak.

As shown in FIG. 1, the package 100 can have a width w_(p) (e.g.,dimension extending in the x direction), length (not shown) (e.g.,dimension extending in the y direction), and thickness t_(p) (dimensionextending in the z direction). When this example package 100 is used asa package for an energy storage device, the dimensions of the device canbe defined by the dimensions of the package 100. For example, the widthof the device can be defined by the width w_(p) of the package, thelength of the device can be defined by the length of the package 100,and the thickness of the device can be defined by the thickness t_(p) ofthe package 100.

As also shown in FIG. 1, when this example package 100 is used as thepackage for an energy storage device, the device can include regions ofunused space (e.g., regions 125 above each side seal 120). Accordingly,for devices utilizing a package such as the package 100 shown in FIG. 1,there is room to improve the packaging efficiency and energy density bydecreasing the unused space in the device.

FIGS. 2-4 schematically illustrate cross-sectional views of exampleenergy storage device packages with folded side seals. As shown in FIG.2, when a side seal 220 has a width w_(s), (e.g., when unfolded) that issmaller than the package thickness t_(p) (e.g., w_(s)<t_(p)), the sideseal 220 can be folded up. Compared to when a side seal 220 is unfolded,this example package 200 can have a reduced package width w′_(p) andreduced unused space 225 in the device. When a side seal has a widthw_(s) that is larger than the package thickness t_(p) (e.g.,w_(s)>t_(p)), the side seal can be folded on a side of the package withmultiple folds. For example, FIG. 3 shows a package 300 having a sideseal 320 with a double fold (e.g, 1 fold up and 1 fold down). As anotherexample, FIG. 4 shows a package 400 having a side seal 420 with a triplefold (e.g., 1 fold up, 1 fold down, and 1 fold up). Compared to when theside seals 320, 420 are unfolded, these example packages 300, 400 canalso have a reduced package width w′_(p) and reduced unused space 325,425. However, with a package having very a small thickness t_(p) (e.g.,designed for a relatively thin energy storage device), it can bedifficult to crease and fold the side seals 320, 420 into folds withsuch a small size (e.g., folds≈t_(p)). Such folded packages can requireadditional equipment and can have quality issues (e.g., leaking).

FIG. 5 schematically illustrates a cross-sectional view of anotherexample energy storage device package with side seals. As shown in theexample package 500 in FIG. 5, when a side seal 520 (when unfolded) hasa width w_(s) that is larger than the package thickness t_(p) (e.g.,w_(s)>t_(p)), the side seal 520 can be folded on the package 500 (e.g.,on the top of the package 500). Compared to when the side seal 520 isunfolded, such a package 500 can have a reduced package width w′_(p).However, folding a side seal 520 this way can increase the packagethickness t_(p)′ and can add unused space 525 in the device (e.g.,between the folded side seals 520 on top of the package 500 as shown inFIG. 5). Accordingly, for devices utilizing these example packages shownin FIGS. 1-5, there is room to improve (e.g., maximize) the packagingefficiency and energy density by decreasing (e.g., minimizing) theunused space in the device.

FIGS. 6A-6B schematically illustrate cross-sectional views of an exampleenergy storage device package with side seals in accordance with certainembodiments described herein. FIG. 6A shows the example package 600 withthe side seals 620 unfolded, and FIG. 6B shows the example package 600with the side seals 620 folded. The example package 600 (e.g., pouch)can include a cell housing portion 610 _(h) and a sealed portion 610_(g). As shown in FIG. 6A, the cell housing portion 610 _(h) can havewalls 610′_(a), 610′_(b) defining an inner region 615. The walls610′_(a), 610′_(b) can be configured to house within the inner region615 an anode, a cathode, a separator, and an electrolyte (not shown).The cell housing portion 610 _(h) can include an indentation 640. Thesealed portion 610 _(s) can extend from the cell housing portion 610_(h). As shown in FIG. 6B, the sealed portion 610 _(s) can be foldedonto the cell housing portion 610 _(h) such that part of the sealedportion 610 _(s) can reside in the indentation 640. As described herein,a device utilizing such a package can have increased (e.g.,substantially maximized in some cases) packaging efficiency and energydensity by having reduced (e.g., substantially minimized in some cases)unused space.

FIG. 6C schematically illustrates a perspective view of an exampleenergy storage device utilizing the example package 600 shown in FIGS.6A-6B. As shown in FIG. 6C, in various embodiments, the energy storagedevice 601, such as an electrochemical cell (e.g., a battery) caninclude the example package 600 having the cell housing portion 610 _(h)and the sealed portion 610 _(s). The cell housing portion 610 _(h) canbe configured to house a stack of electrodes 605 within an inner region615 of the cell housing portion 610 _(h). Each electrode 605 can havedimensions of width w_(e), length l_(e), and thickness t_(e). One ormore electrodes 605′ can have at least one of the dimensions (e.g.,w′_(e), l′_(e), and/or t′_(e)) smaller than a corresponding dimension(e.g., w″_(e), l″_(e), and/or t″_(e)) of other electrodes 605″ in thestack of electrodes 605. In the example energy storage device 601 shownin FIG. 6C, the electrode 605′ has a width w′_(e) that is smaller thanthe width w″_(e) of the other electrode 605″.

By having one or more electrodes 605′ having at least one of thedimensions smaller than a corresponding dimension of the otherelectrodes 605″ in the stack of electrodes 605, the indentation 640 onthe cell housing portion 610 _(h) can be disposed adjacent the one ormore electrodes 605′ having the at least one smaller dimension. Forexample, the indentation 640 can form a stepped region 640 _(step)(e.g., in the inner region 615) that is complimentary to one or moreelectrodes 605′ having at least one of the dimensions smaller than acorresponding dimension of the other electrodes 605″ in the stack ofelectrodes 605.

The sealed portion 610 _(s) can be folded onto the cell housing portion610 _(h) so that at least a part of the sealed portion 610 _(s) canreside in the indentation 640. Compared to the example shown in FIG. 5,the example embodiment shown in FIG. 6C can provide sealed portions 610_(s) that can be folded on the cell housing portion 610 _(h) withoutincreasing the thickness t_(p) of the package 600, and hence alsowithout increasing the thickness t_(d) of the device 601. For example,instead of occupying additional space above the cell housing portion 610_(h), sealed portions 610 _(s) can reside in spaces which would havebeen occupied by one or more electrodes 605′ had they have similardimensions as the other electrodes 605″ in the stack of electrodes 605.Since the unused space in the embodiment shown in FIG. 6C is reduced,the packaging efficiency and energy density can be improved.

In certain embodiments, the energy storage device 601 can include abattery. The battery can be either a secondary battery (e.g.,rechargeable) or a primary battery (e.g., non-rechargeable). The batteryis not particularly limited and can include those known in the art oryet to be developed. For example, the battery can include a lithium ionbattery, a lithium polymer battery, or a metal lithium battery. Invarious embodiments, the battery can be implemented as a pouch cell.

As described herein, the energy storage device 601 can include aplurality of electrodes 605 within the inner region 615 of the cellhousing portion 610 _(h). The plurality of electrodes 605 can bearranged to form a stacked configuration, e.g., a stack of electrodes605 with electrodes 605 disposed on top of one another. The electrodes605 can include one or more anodes and/or one or more cathodes. Theelectrodes 605 can include electrochemically active material. Thecomposition of the electrodes 605 is not particularly limited and caninclude electrode materials known in the art or yet to be developed. Forexample, the electrodes 605 can be selected based on the desiredapplication and/or performance. In various embodiments, the one or moreof the electrodes 605 can include silicon composite material, carboncomposite material, and/or silicon-carbon composite material such asthose described in U.S. patent application Ser. No. 13/008,800 entitled“Composite Materials for Electrochemical Storage,” U.S. patentapplication Ser. No. 13/601,976 entitled “Silicon Particles for BatteryElectrodes,” and/or U.S. patent application Ser. No. 13/799,405 entitled“Silicon Particles for Battery Electrodes,” each of which are expresslyincorporated herein. In some embodiments, one or more electrodes 605 caninclude self-supported monolithic structures. For example, the electrode605 can include a composite material including a substantiallycontinuous phase comprising hard carbon and holding the compositematerial together. In some embodiments, one or more electrodes 605 caninclude a current collector such as a copper sheet. For example, in somesuch embodiments, an anode can be in contact with a negative currentcollector, and/or a cathode can be in contact with a positive currentcollector. In some embodiments, each negative current collector can haveone anode attached to each side; each positive current collector canhave one cathode attached to each side.

In various embodiments, the shapes and/or sizes of the anodes andcathodes can be the same or different from each other. In someembodiments, an anode and a cathode can be slightly different in size.For example, in lithium ion configurations where the metal oxide carriesthe lithium into the electrochemical cell, the cathode can be undersizedcompared to the anode. This can help prevent dendrite formation andlithium plating in some embodiments. For example, when lithium ions movefrom the cathode to the anode, if there is no anode to receive thelithium ions, the lithium ions could plate as a solid. The shapes and/orsizes of an anode and cathode are not particularly limited and can beselected based on the desired application and/or performance.

Each electrode 605 can have dimensions of width w_(e), length l_(e), andthickness t_(e). In the example shown in FIG. 6C, the dimension of widthw_(e) can correspond to the dimension of the electrode 605 extendinghorizontally in the cross-sectional plane (e.g., in the x direction).The dimension of length l_(e) can correspond to the dimension of theelectrode 605 extending into the page perpendicular to thecross-sectional plane (e.g., in the y direction). The length l_(e) istypically longer than the width w_(e). The dimension of thickness t_(e)can correspond to the dimension of the electrode 605 extendingvertically in the cross-sectional plane (e.g., in the z direction).Other conventions for defining width w_(e), length l_(e), and thicknesst_(e) are possible. The actual dimensions of width w_(e), length l_(e),and thickness t_(e) are not particularly limited and can be selected forthe intended application and/or desired performance.

One or more electrodes 605′ can have at least one of the dimensions(e.g., w′_(e), l′_(e), and/or t′_(e)) smaller than a correspondingdimension (e.g., w″_(e), l_(e), and/or t″_(e)) of other electrodes 605″in the stack of electrodes 605. For example, as shown in FIG. 6C, theuppermost electrode (or electrodes) 605′ has a dimension smaller than acorresponding dimension of the other electrodes 605″. The one or moreelectrodes 605′ can include an anode and/or a cathode. The one or moreelectrodes 605′ can include an electrode pair (e.g., an anode and acathode). In this particular example, the uppermost electrode 605′ canhave a width w′_(e) smaller than the width w″_(e) of the otherelectrodes 605″. In some embodiments, the length l′_(e) of one or moreelectrodes 605′ can be smaller than the length l_(e) of the otherelectrodes 605″. In some embodiments, the thickness t′_(e) of one ormore electrodes 605′ can be smaller than the thickness t″_(e) of theother electrodes 605″. The actual dimensions of the smaller widthw′_(e), length l′_(e), and/or thickness t′_(e) of the one or moreelectrodes 605′ are not particularly limited and can be selected suchthat at least a part of the sealed portion 610 _(s) can be disposedwithin the space created by having the smaller electrode or electrodes605′. In various embodiments, the dimensions of the smaller widthw′_(e), length l′_(e), and/or thickness t′_(e) of the one or moreelectrodes 605′ can be sized such that there is just enough room for thesealed portion 601 _(s) to fold onto the cell housing portion 610 _(h)and fit into the indentation 640. For example, in some embodiments, thewidth w′_(e), of the smaller electrode 605′ can be smaller than thecorresponding width w″_(e) of the other electrodes 605″ by approximatelytwice the width w_(s) of the sealed portion 610 _(s) minus twice thethickness t_(d) of the device 601.

In various embodiments, the energy storage device 601 can include aseparator separating each anode and cathode. For example, the separatorcan be shaped and/or dimensioned such that it can be positioned betweenadjacent electrodes 605 in the electrode stack to provide desiredseparation between the adjacent electrodes 605. The separator can beconfigured to facilitate electrical insulation between an anode andcathode, while permitting ionic transport between the anode and thecathode. The composition of the separator is not particularly limitedand can include those known in the art or yet to be developed. In someembodiments, the separator can comprise a porous material, including aporous polyolefin material.

The stack of electrodes 605 can be in contact with an electrolyte. Insome embodiments, the stack of electrodes 605 can be immersed inelectrolyte. The electrolyte can serve to facilitate ionic transportbetween an anode and a cathode. The composition of the electrolyte isnot particularly limited and can include those known in the art or yetto be developed. For example, the composition of the electrolyte can beselected based on the application and/or desired performance. In someembodiments, the electrolyte can include a nonaqueous electrolytesolution. For example, the electrolyte can include a carbonate solvent.

As shown in FIGS. 6A-6C, the energy storage device 600 can include walls610′_(a), 610′_(b) to define an inner region 615 of the cell housingportion 610 _(h). In various embodiments, the walls 610′_(a), 610′_(b)can be configured to house within the inner region 615 an anode, acathode, a separator, and an electrolyte. The cell housing portion 610_(h) can include at least one indentation 640. In some embodiments, thewalls 610′_(a), 610′_(b) of the cell housing portion 610 _(h) cancomprise a flexible material. For example, the walls 610′_(a), 610′_(b)of the cell housing portion 610 _(h) may readily deform upon applicationof pressure on the walls 610′_(a), 610′_(b), including pressure exertedupon the walls 610′_(a), 610′_(b) from outside and from within thepackage 600. The walls 610′_(a), 610′_(b) of the cell housing portion610 _(h) can also readily deform to follow the shape of the stack ofelectrodes 605 such that the walls 610′_(a), 610′_(b) can form one ormore indentations 640 adjacent the one or more smaller electrodes 605′.For example, the example embodiment shown in FIG. 6C includes twoindentations (e.g., one on the left and one on the right) in wall610′_(a). The indentation 640 can form a stepped region 640 _(step) inthe inner region 615 of the cell housing portion 610 _(h). In someembodiments, the walls 610′_(a), 610′_(b) of the cell housing portion610 _(h) may comprise the same material. In some other embodiments, thewalls 610′_(a), 610′_(b) of the cell housing portion 610 _(h) maycomprise different materials. In various embodiments, one or more of thewalls 610′_(a), 610′_(b) of the cell housing portion 610 _(h) maycomprise aluminum. For example, one or more of the walls 610′_(a),610′_(b) of the cell housing portion 610 _(h) may comprise an aluminumlaminated pouch material.

As shown in FIG. 6A, the walls 610′_(a), 610′_(b) of the cell housingportion 610 _(h) can have a wall thickness t_(a), t_(b). One or more ofthe walls 610′_(a), 610′_(b) of the cell housing portion 610 _(h) canhave the same or different wall thickness t_(a), t_(b) from each other.In some embodiments, one or more of the walls 610′_(a), 610′_(b) of thecell housing portion 610 _(h) can have a thickness t_(a), t_(b) in therange of about 50 microns to about 220 microns, or in a range betweenthe foregoing values, such as of about 70 microns to about 200 microns(e.g., about 70 microns, about 80 microns, about 90 microns, about 100microns, about 110 microns, about 120 microns, about 130 microns, about140 microns, about 150 microns, about 160 microns, about 170 microns,about 180 microns, about 190 microns, about 200 microns, or any value inbetween). Other values are possible.

As shown in FIG. 6C, the energy storage device 601 can also include asealed portion 610 _(s) extending from the cell housing portion 610_(h). The sealed portion 610 _(s) can be formed by sealing portions 620of one or more walls 610′_(a), 610′_(b) of the cell housing portion 610_(h). As described herein with respect to the cell housing portion 610_(h), the walls 610′_(a), 610′_(b) of the sealed portion 610 _(s) cancomprise a flexible material. For example, the sealed walls 610′_(a),610′_(b) may readily fold onto the cell housing portion 610 _(h) uponapplication of pressure on the sealed portion 610 _(s). The sealed walls610′_(a), 610′_(b) may also readily fold into an indentation 640.Accordingly, as described herein with respect to the cell housingportion 610 _(h), in some embodiments, one or more walls 610′_(a),610′_(b) of the sealed portion 610 _(s) may comprise aluminum. Forexample, one or more walls 610′_(a), 610′_(b) of the sealed portion 610_(s) may comprise an aluminum laminated pouch material. In variousembodiments, the sealed portion 610 _(s) can be formed by heat sealingthe one or more walls 610′_(a), 610′_(b). In some embodiments, thesealed portion 610 _(s) can be hermetically sealed.

FIG. 6C shows the sealed portion 610 _(s) including two sealed portions(e.g., one on the left and one on the right). In various embodiments,the sealed portions 610 _(s) can include three, four, or more portions.As shown in FIG. 6C, the sealed portion 610 _(s) can be folded onto thecell housing portion 610 _(h) so that part of the sealed portion 610_(s) can reside in the indentation 640. FIG. 6C shows two sealed portion610 _(s) with each residing in its own separate indentation 640. Inother embodiments, each sealed portion 610 _(s) can reside in a commonindentation 640.

The sealed portion 610 _(s) can have a width w_(s), length L_(s), andthickness t_(s). Example definitions for the width w_(s), length l_(s),and thickness t_(s) are provided herein. However, other conventions fordefining width w_(s), length l_(s), and thickness t_(s) are possible.

As shown in FIGS. 6A-6C, the width w_(s) of the sealed portion 610 _(s)can correspond to the amount of seal 620 between the walls 610′_(a),610′_(b) of the sealed portion 610 _(s) extending from the cell housingportion 610 _(h) in the x direction when unfolded (e.g., in thedimension extending horizontally in the cross-sectional plane whenunfolded). The width w_(s) of the sealed portion 610 _(s) can besufficient to seal the walls 610′_(a), 610′_(b) together such that thesealed portion 610 _(s) does not leak. In various embodiments, if thewidth w_(s) of the sealed portion 610 _(s) is too wide, space can bewasted. However, if the width w_(s) of the sealed portion 610 _(s) istoo narrow, the sealed portion 610 _(s) could leak and cause areliability or safety issue. In some embodiments, the sealed portion 610_(s) can have a width w_(s) in the range of about 1 mm to about 15 mm,or in a range between the foregoing values, such as of about 1.5 mm toabout 10 mm (e.g., about 1.5 mm, about 2 mm, about 2.5 mm, about 3 mm,about 3.5 mm, about 4 mm, about 4.5 mm, about 5 mm, about 5.5 mm, about6 mm, about 6.5 mm, about 7 mm, about 7.5 mm, about 8 mm, about 8.5 mm,about 9 mm, about 9.5 mm, about 10 mm, or any value in between). Othervalues are possible. The width w_(s) of the sealed portion 610 _(s) canbe selected based on the desired application and/or performance.

The length l_(s) of the sealed portion 610 _(s) can correspond to theamount of seal between the walls 610′_(a), 610′_(b) of the sealedportion 610 _(s) extending in the y direction when unfolded (e.g., inthe dimension extending into the page perpendicular to thecross-sectional plane when unfolded). The length l_(s) is typicallylonger than the width w_(s). In some embodiments, the sealed portion 610_(s) can have a length l_(s) in the range of about 1 mm to about 15 mm,or in a range between the foregoing values, such as of about 2 mm toabout 12 mm, of about 2 mm to about 10 mm (e.g., about 2 mm, about 2.5mm, about 3 mm, about 3.5 mm, about 4 mm, about 4.5 mm, about 5 mm,about 5.5 mm, about 6 mm, about 6.5 mm, about 7 mm, about 7.5 mm, about8 mm, about 8.5 mm, about 9 mm, about 9.5 mm, about 10 mm, or any valuein between). For some electrochemical cells for mobile applications, thelength l_(s) can be in the range of about 1 mm to about 5 mm. The lengthl_(s) of the sealed portion 610 _(s) can be selected based on thedesired application and/or performance.

The thickness t_(s) of the sealed portion 610 _(s) can correspond to thedimension extending in the z direction when unfolded (e.g., in thedimension extending vertically in the cross-sectional plane whenunfolded). In some embodiments, since walls 610′_(a), 610′_(b) can besealed to form the sealed portion 610 _(s) the sealed portion 610 _(s)can have a thickness t_(s) that is approximately equal to the sum of thethicknesses t_(a), t_(b) of the sealed walls 610′_(a), 610′_(b). Forexample, in some embodiments where the thicknesses t_(a), t_(b) of thesealed walls 610′_(a), 610′_(b) are substantially the same, thethickness t_(s) of the sealed portion 610 _(s) can be approximatelytwice the thickness t_(a), t_(b) of the either one of the sealed walls610′_(a), 610′_(b) (for example, t_(s)≈2×t_(a) or 2×t_(b)).

However, in some other embodiments, the thickness t_(s) of the sealedportion 610 _(s) can be modified by sealing walls 610′_(a), 610′_(b) forthe sealed portion 610 _(s) having different thicknesses t_(a), t_(b)such that the sum of the thicknesses t_(a), t_(b) provide the desiredthickness t_(s) for the sealed portion 610 _(s). The thickness t_(s) ofthe sealed portion 610 _(s) can be selected based on the desiredapplication and/or performance.

In certain embodiments, the energy storage device 601 has a first majorexterior surface 601, a second major exterior surface 602, and an energystorage device thickness t_(d) extending therebetween. In variousembodiments, the width w_(s) of the sealed portion when unfolded can belarger than the thickness of the energy storage device t_(d). In variousembodiments, the sealed portion 610 _(s) can be folded adjacent thefirst major surface 601 (e.g., against the cell housing portion 610 _(h)near the first major surface 601). In some embodiments, the sealedportion 610 _(s) can also be folded on the cell housing portion 610 _(h)near the second major surface 602. For example, the indentation 640 canbe located adjacent the second major surface 602 and the seal portion610 _(s) can also be folded onto the cell housing portion 610 _(h) nearthe second major surface 602.

In such examples, compared to the example in FIG. 5, the sealed portions610 _(s) can be folded on the cell housing portion 610 _(h) withoutincreasing the thickness of the device t_(d). For example, by having thesmaller electrode 605′, the cell housing portion 610 _(h) can form anindentation 640 adjacent the smaller electrode 605′. The sealed portion610 _(s) can be folded onto the cell housing portion 610 _(h) so that atleast part of the sealed portion 610 _(s) can reside in the indentation640. Accordingly, even though the width w_(s) of the sealed portion 610_(s) can be larger than the thickness of the energy storage devicet_(d), the sealed portion 610 _(s) can reside in space that would havebeen occupied by electrodes 605 in a stack of electrodes 605 having thesame dimensions. As such, unused space can also be reduced (andminimized in some cases).

The actual width w_(s), length l_(s), and thickness t_(s) dimensions forthe sealed portion 610 _(s) can be designed such that part of the sealedportion 610 _(s) can reside within the indentation 640 with a singlelayer of the sealed portion 610 _(s) (e.g., as shown in FIGS. 6B-6C). Inother embodiments, the width w_(s), length l_(s), and thickness t_(s)dimensions can result in part of the sealed portion 610 _(s) beingfolded in multiple layers with at least a part of the sealed portion 610_(s) residing in an indentation 640 (e.g., similar to the examples shownin FIGS. 3 and 4 but with a part of the sealed portion 610 _(s) residingin an indentation 640). In various embodiments, the sealed portion 610_(s) can be attached onto the cell housing portion 610 _(h) (e.g., usingglue).

In some embodiments, the energy storage device 601 may comprise an anodeconnector (not shown) and a cathode connector (not shown) configured toelectrically couple the anodes and the cathodes of the electrode stackto an external circuit, respectively. The anode connector and/or acathode connector may be affixed to the walls 610′_(a), 610′_(b) of thecell housing portion 610 _(h) or to the walls 610′_(a), 610′_(b) of thesealed portion 610 _(s) to facilitate electrical coupling of the energystorage device 601 to an external circuit. The anode connector and/orthe cathode connector may be affixed to a wall 610′_(a), 610′_(b) alongone edge of the cell housing portion 610 _(h) and/or the sealed portion610 _(s). The anode connector and/or the cathode connector can beelectrically insulated from one another, and from the cell housingportion 610 _(h) and/or the sealed portion 610 _(s). For example, atleast a portion of each of the anode connector and/or the cathodeconnector can be within an electrically insulating sleeve such that theconnectors can be electrically insulated from one another and from thecell housing portion 610 _(h) and/or the sealed portion 610 _(s).

Certain embodiments described herein relate to the energy storage device601, e.g., a pouched energy storage device. Various embodimentsdescribed herein also relate to a pouch for an energy storage device 601as shown in FIGS. 6A-6B. For example, the pouch can include the cellhousing portion 610 _(h) and the sealed portion 610 _(s) as describedherein. The cell housing portion 610 _(h) can have walls 610′_(a),610′_(b) defining an inner region 615. The walls 610′_(a), 610′_(b) canbe configured to house within the inner region 615 an anode, a cathode,a separator, and an electrolyte. The cell housing portion 610 _(h) caninclude an indentation 640. The sealed portion 610 _(s) can extend fromthe cell housing portion 610 _(h). The sealed portion 610 _(s) can befolded onto the cell housing portion 610 _(h) such that part of thesealed portion 610 _(s) can resides in the indentation 640.

As shown in FIG. 7, certain embodiments described herein also relate toa method 700 of making a pouched energy storage device. As shown inoperational block 710, the method 700 can include providing walls610′_(a), 610′_(b) to define an inner region 615 of the cell housingportion 610 _(h). The walls 610′_(a), 610′_(b) can be configured tohouse within the inner region 615 an anode, a cathode, a separator, andan electrolyte. As shown in operational block 720, the method 700 canalso include inserting a stack of electrodes 650 into the cell housingportion 610 _(h). Each electrode 605 can have dimensions of width w_(e),length l_(e), and thickness t_(e). One or more electrodes 605′ can haveat least one of the dimensions (e.g., w′_(e), l′_(e), and/or t′_(e))smaller than a corresponding dimension (e.g., w″_(e), l_(e), and/ort″_(e)) of other electrodes 605″ in the stack of electrodes 605. Asshown in operational block 730, the method 700 can further include heatsealing portions of the walls 610′_(a), 610′_(b) to form the sealedportion 610 _(s). As shown in operational block 740, the method 700 canfurther include folding the sealed portion 610 _(s) onto the cellhousing portion 610 _(h) such that part of the sealed portion 610 _(s)resides in an indentation 640 of the cell housing portion 610 _(h).

In various embodiments, the method 700 can further include forming theindentation 640 on the cell housing portion 610 _(h). In variousembodiments, the indentation 640 can be formed after inserting the stackof electrodes 650 into the cell housing portion 610 _(h). Alternatively,in some embodiments, the indentation 640 can be formed before insertingthe stack of electrodes 650 into the cell housing portion 610 _(h). Theindentation 640 can be sized to accommodate at least part of the sealedportion 610 _(s). The indentation 640 can define a stepped region in theinner region 615.

In some embodiments, providing the walls 610′_(a), 610′_(b) can compriseproviding aluminum laminate pouch material. Heat sealing portions of thewalls 610′_(a), 610′_(b) can comprise hermetically sealing the portionsof the walls 610′_(a), 610′_(b). In addition, folding the sealed portion610 _(s) onto the cell housing portion 610 _(h) can include folding afirst region of the sealed portion 610 _(s) adjacent a first majorsurface 601 of the device 601, and folding a second region of the sealedportion 610 _(s) adjacent a second major surface 602 of the device 601.The method 700 can also include attaching the sealed portion 610 _(s)onto the cell housing portion 610 _(h).

Various embodiments have been described above. Although the inventionhas been described with reference to these specific embodiments, thedescriptions are intended to be illustrative and are not intended to belimiting. Various modifications and applications may occur to thoseskilled in the art without departing from the true spirit and scope ofthe invention as defined in the appended claims.

What is claimed is:
 1. A pouched energy storage device comprising: acell housing portion and a sealed portion; a stack of electrodes housedwithin an inner region of the cell housing portion, each electrodehaving dimensions of width, length, and thickness, wherein one or moreelectrodes have a first width and one or more other electrodes have asecond width that is smaller than the first width; an indentation on thecell housing portion adjacent the sealed portion, wherein theindentation forms a stepped region in the inner region wherein a widthof the stepped region is half a difference between the first width andthe second width; and wherein the sealed portion is folded onto the cellhousing portion so that at least a part of the sealed portion resides inspace resulting from the second width being smaller than the firstwidth.
 2. The device of claim 1, wherein the device is a lithium ionbattery, a lithium polymer battery, or a metal lithium battery.
 3. Thedevice of claim 1, wherein walls of the cell housing portion have a wallthickness, and the sealed portion has a sealed portion thickness that isapproximately twice the wall thickness of the walls of the cell housingportion.
 4. The device of claim 1, wherein the device comprises at leasttwo sealed portions.
 5. The device of claim 1, comprising a first majorexterior surface, a second major exterior surface, and a devicethickness extending therebetween, wherein the sealed portion has asealed portion width, a sealed portion length, and a sealed portionthickness, and wherein the device thickness is smaller than the sealedportion width.
 6. The device of claim 5, wherein the sealed portionwidth is in the range of about 1.5 mm to about 10 mm.
 7. The device ofclaim 1, wherein the device comprises a first major surface and a secondmajor surface, and wherein the sealed portion is folded adjacent thefirst major surface of the device and the indentation is locatedadjacent the second major surface of the device.
 8. The device of claim1, wherein the sealed portion is folded to form multiple layers.
 9. Thedevice of claim 1, wherein the sealed portion is attached onto the cellhousing portion.
 10. A method of making a pouched energy storage device,comprising: providing walls to define an inner region of the cellhousing portion, the walls configured to house within the inner regionan anode, a cathode, a separator, and an electrolyte; inserting a stackof electrodes into the cell housing portion, each electrode havingdimensions of width, length, and thickness, wherein one or moreelectrodes have a first width and one or more other electrodes have asecond width that is smaller than the first width; heat sealing portionsof the walls to form the sealed portion; and folding the sealed portiononto the cell housing portion such that part of the sealed portionresides in an indentation of the cell housing portion, wherein a widthof the indentation is half a difference between the first width and thesecond width.
 11. The method of claim 10, further comprises: forming theindentation on the cell housing portion, wherein the indentation issized to accommodate at least part of the sealed portion.
 12. The methodof claim 10, wherein the indentation defines a stepped region in theinner region.
 13. The method of claim 10, wherein providing wallscomprises providing aluminum laminate pouch material.
 14. The method ofclaim 10, wherein heat sealing portions of the walls compriseshermetically sealing the portions of the walls.
 15. The method of claim10, wherein folding the sealed portion onto the cell housing portioncomprises: folding a first region of the sealed portion adjacent a firstmajor surface of the housing portion; and folding a second region of thesealed portion adjacent a second major surface of the housing portion.16. The method of claim 10, further comprising attaching the sealedportion onto the cell housing portion.
 17. A pouch for an energy storagedevice comprising: a cell housing portion having walls defining an innerregion, the walls configured to house within the inner region an anode,a cathode, a separator, and an electrolyte, the cell housing portioncomprising an indentation; and a sealed portion extending from the cellhousing portion, wherein the sealed portion is folded onto the cellhousing portion such that part of the sealed portion resides in theindentation, wherein a width of the indentation is half a differencebetween a width of one or more electrodes that is smaller than a widthof one or more other electrodes in a stack of electrodes.
 18. The pouchof claim 17, wherein the walls are configured to house a lithium ionbattery, a lithium polymer battery, or a metal lithium battery.
 19. Thepouch of claim 17, wherein the walls of the cell housing portion and thesealed portion comprise an aluminum laminate pouch material.
 20. Thepouch of claim 17, wherein the indentation forms a stepped region in theinner region of the cell housing portion.
 21. The pouch of claim 17,wherein the walls of the cell housing portion have a wall thickness, andthe sealed portion has a sealed portion thickness that is approximatelytwice the wall thickness of the walls of the cell housing portion. 22.The pouch of claim 17, wherein the pouch comprises at least two sealedportions.
 23. The pouch of claim 17, wherein the pouch comprises a firstmajor exterior surface, a second major exterior surface, and a pouchthickness extending therebetween, wherein the sealed portion has asealed portion width, a sealed portion length, and a sealed portionthickness, and wherein the pouch thickness is smaller than the sealedportion width.
 24. The pouch of claim 23, wherein the sealed portionwidth is in the range of about 1.5 mm to about 10 mm.
 25. The pouch ofclaim 17, wherein the pouch comprises a first major surface and a secondmajor surface, and wherein the sealed portion is folded adjacent thefirst major surface of the pouch and the indentation is located adjacentthe second major surface of the pouch.
 26. The pouch of claim 17,wherein the sealed portion is folded to form multiple layers.
 27. Thepouch of claim 17, wherein the sealed portion is attached onto the cellhousing portion.